CN113984979A - Apple powder reference substance containing pesticide residues and preparation method thereof - Google Patents
Apple powder reference substance containing pesticide residues and preparation method thereof Download PDFInfo
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Abstract
The invention relates to an apple powder reference substance containing pesticide residues and a preparation method thereof. The method comprises the following steps: adding maltodextrin, silicon dioxide and cellulose powder into the apple pulp added with the standard amount of pesticide, and then carrying out vacuum freeze drying, crushing and sieving to obtain the apple pulp. Its advantages are: the raw materials and the mixture ratio of the raw materials are optimized, the finally prepared substance not only has high pesticide recovery rate and obviously reduces the caking rate, but also realizes good stability of the pesticide content within 60 days under the freezing condition (-15 ℃). The invention has positive effects on promoting the development of the food matrix reference substance development technology in China and perfecting the food safety monitoring and detecting technology system in China.
Description
Technical Field
The invention relates to the technical field of fruit and vegetable matrix reference substances, in particular to an apple powder reference substance containing pesticide residues and a preparation method thereof.
Background
In order to prevent and control plant diseases and insect pests, the pesticide is widely applied in agricultural production. However, pesticide residues in food and environment have a certain influence on human health, and have attracted attention. Pesticide residue detection in food is also a key item in detection in the field of food safety. The food inspection mechanisms in China are numerous, and the inspection levels and the inspection capabilities of the mechanisms are different. How to ensure that detection results provided by different laboratories, different methods and different detectors are accurate is an urgent problem to be solved for detecting pesticide residues in food. General requirements for testing and calibrating laboratory capabilities (GB/T27025-2008) of the national standard takes standard reference substances as a preferential selection method for controlling laboratory quality and ensuring data consistency, and matrix reference substances are also internationally accepted effective means for evaluating the consistency of test results. However, the research and development of chemical pollutant matrix reference substances in food in China are relatively late, the outstanding problems of lack of quantity, single type, unreasonable magnitude level, late preparation and value determination method and the like exist, and the actual requirements of data consistency evaluation in food safety monitoring and detection and risk assessment in China cannot be met.
China is a big fruit producing country, and the apple yield is the first place in the world. The apple has high nutritive value and low calorie, is rich in minerals and vitamins, is suitable for people of all ages, and is one of the fruits which are often eaten by people. However, the apple is easy to have diseases and insect pests in the growth process, and various pesticides are applied to control the diseases and insect pests at present. Therefore, apple is a representative fruit sample matrix. The development of the apple powder reference substance containing pesticide residues has important significance for development of a detection method, quality control of a detection process, laboratory capability verification, comparison among laboratories and the like. However, at present, no reference substance of the pesticide residue matrix related to apple powder is found in national standard substance resource sharing platform, FAPAS institute of detection and technology (FAPAS) website in british, National Institute of Standard Technology (NIST) website in usa, and united research center standard substance and measurement research Institute (IRMM) website in european union committee, and only similar "standard substance for analyzing pyrethroid pesticide component in concentrated apple juice" and "pesticide quality control sample of apple jam matrix" are found. As is well known, apple powder is easier to store, transport and take compared with concentrated apple juice and apple jam, but because the sugar content of apples is higher, the glass transition temperature is lower, and the apple powder is easy to agglomerate in the long-term storage process, the preparation of reference substances of apple powder substrates is difficult, and the preparation of reference substances of pesticide residues of apple powder substrates is very important under the condition that the production mode and additives do not influence pesticide residues.
Polymers can be classified into 3 mechanical states, i.e., glassy state, rubbery state, and viscous state, depending on the temperature region of the amorphous polymer. When the temperature is lower, the thermal movement energy of polymer molecules is very low, and the molecules in the long polymer chains are in a frozen state in a random mode and have a solid-like appearance and a liquid-like microstructure. This state is called the glassy state. However, when the temperature is increased to a certain temperature, segmental motion of molecules is excited, and the polymer becomes sticky and flexible, and this state is called a rubbery state. When the temperature continues to rise, the entire molecular segment can move and the polymer exhibits viscous flow, a state referred to as viscous flow. When the fruit and vegetable powder is in a glass state, the fruit and vegetable powder has stable properties in all aspects, and is very favorable for maintaining the quality such as storage, freshness and the like of the fruit and vegetable powder; when the fruit and vegetable powder is transformed from a glass state to a rubber state, the physical and chemical changes of the fruit and vegetable powder, such as texture, microbial activity, enzyme activity and the like, are caused, and the appearance phenomenon is agglomeration. Therefore, the agglomeration phenomenon of the apple powder can be improved by increasing the glass transition temperature. The glass transition temperature of a food product is positively correlated with its relative molecular mass. The apple pulp concentrate contains a large amount of small molecular sugar and organic acid, so that the glass transition temperature of the apple pulp concentrate is low. Researches show that substances such as maltodextrin, starch, Arabic gum and the like have higher glass transition temperature, if the substances are added, the comprehensive glass transition temperature of the product can be improved, and the caking phenomenon can be improved.
Besides increasing the glass transition temperature, the addition of an anticaking agent (cellulose powder, silicon dioxide, tricalcium phosphate and the like) can also improve the caking phenomenon of the apple powder to a certain extent. The action mechanism is divided into: (1) physical barrier. When the surfaces of the main base material particles are covered by the anticaking agent particles, the anticaking agent layer naturally provides a barrier effect due to small acting force among the anticaking agents; (2) competing with the primary matrix particles. The anticaking agent and the main base material particles compete for moisture absorption, so that the absorption of moisture and the like by the product is reduced; (3) eliminating static charge and molecular force on the surface of the base material. The anticaking agent improves the flowability of the powder by eliminating static charge and molecular force on the surface of a main base material; (4) causing the host matrix to change lattice to form a fragile structure.
The Chinese patent application: CN201811094865.3 discloses a method for preparing a sample for verifying pesticide residue capability in a laboratory and an application thereof, relating to the field of pesticide residue detection. The patent adopts a freeze-drying technology, matrix samples which are cut up and homogenized evenly are freeze-dried, crushed and sieved to prepare even matrix freeze-dried powder, pesticide standard substances with specific concentration are uniformly sprayed in proportion, and the mixture is freeze-dried, crushed, sieved and subpackaged. However, the patent can only meet the stability of a high-sugar sample for about 60 days, and the apple powder caking phenomenon appears along with the prolonging of the storage time, so that the accuracy of a measuring result is influenced.
The Chinese patent application: CN201110064951.1 discloses a sample pretreatment method, a pesticide detection method and a detection box suitable for detecting pesticide residues by an enzyme inhibition method. The method comprises the steps of crushing a sample to be detected, adding an extracting solution, and oscillating to transfer pesticide residues in the sample to the extracting solution; adding pesticide residue intensifier into the extract, and reacting. However, the product obtained by the process of this patent is less stable.
Aiming at the defects of the prior art, the caking rate of the apple powder reference substance prepared by the technology is reduced by 11.42%, and the sample caking phenomenon does not occur through the stability test for half a year, so that the accuracy of the measurement result is ensured.
Disclosure of Invention
The invention aims to provide an apple powder reference substance containing pesticide residues and a preparation method thereof aiming at the defects of the prior art.
In order to achieve the purpose, the invention adopts the technical scheme that:
in a first aspect, the invention provides an apple powder reference substance containing pesticide residues, which is prepared from the following raw materials: containing apple pulp added with a certain amount of pesticide, maltodextrin, silicon dioxide and cellulose powder,
the preparation method of the apple powder reference substance containing pesticide residues comprises the following steps:
(1) pretreatment of apples: removing kernels and stalks of organic apples, taking pulp and crushing into apple pulp;
(2) adding pesticide into apple pulp according to the addition amount, and then adding maltodextrin, wherein the addition amount of the maltodextrin is 50% of the soluble solid content in the apple pulp by weight;
(3) pre-freezing, drying and crushing the substance obtained in the step (2);
(4) adding silicon dioxide and cellulose powder into the powder substance obtained in the step (3), wherein the weight parts of the apple powder, the silicon dioxide and the cellulose powder are as follows: apple powder: silicon dioxide: cellulose powder (100: 1): 0.5;
(5) and (4) putting the substance obtained in the step (4) into a headspace bottle, capping the headspace bottle, and storing the headspace bottle at-15 ℃.
Preferably, the prefreezing conditions in step (2) are: controlling the temperature at minus 40 ℃ for 30min, preserving the heat for 210min and keeping the vacuum degree at 0 Pa; the drying conditions are as follows: (1) firstly, controlling the temperature at minus 5 ℃ for 120min, preserving the heat for 1200min and keeping the vacuum degree at 0 Pa; (2) then controlling the temperature at 5 ℃ for 60min, preserving the temperature for 240min and keeping the vacuum degree at 0 Pa; (3) finally, controlling the temperature at 40 ℃ for 120min, preserving the heat for 1200min and keeping the vacuum degree at 0 Pa.
Preferably, the method for detecting the soluble solid content in the step (2) comprises the following steps: apple pulp is taken, and soluble solid is detected by an instrument automatic refractometer (Abbemat350) according to a refractometer method for determining the content of the soluble solid of fruits and vegetables NY/T2637-2014.
Preferably, the preparation method further comprises the detection of a standard substance, and the detection method of the standard substance is as follows: and (4) taking the blank apple pulp, the blank apple powder and the reference apple pulp to detect the pesticide content.
Preferably, the blank apple pulp and the blank apple powder refer to the apple pulp and the apple powder without pesticide and without malt dextrin, silicon dioxide and cellulose powder; the control apple pulp refers to apple pulp with pesticide added, but without maltodextrin, silica and cellulose powder.
Preferably, the preparation method further comprises a performance detection experiment of the obtained reference substance, wherein the performance detection comprises anti-caking performance detection, uniformity detection and stability detection.
In a second aspect, the invention provides a method for preparing an apple powder reference substance containing pesticide residues, comprising the following steps:
(1) pretreatment of apples: removing kernels and stalks of organic apples, taking pulp and crushing into apple pulp;
(2) adding pesticide into apple pulp according to the addition amount, and then adding maltodextrin, wherein the addition amount of the maltodextrin is 50% of the soluble solid content in the apple pulp by weight;
(3) pre-freezing, drying and crushing the substance obtained in the step (2);
(4) adding silicon dioxide and cellulose powder into the powder substance obtained in the step (3), wherein the weight parts of the apple powder, the silicon dioxide and the cellulose powder are as follows: apple powder: silicon dioxide: cellulose powder (100: 1: 0.5) by weight;
(5) and (4) putting the substance obtained in the step (4) into a headspace bottle, capping the headspace bottle, and storing the headspace bottle at-15 ℃.
Preferably, the prefreezing conditions in step (2) are: controlling the temperature at minus 40 ℃ for 30min, preserving the heat for 210min and keeping the vacuum degree at 0 Pa; the drying conditions are as follows: (1) firstly, controlling the temperature at minus 5 ℃ for 120min, preserving the heat for 1200min and keeping the vacuum degree at 0 Pa; (2) then controlling the temperature at 5 ℃ for 60min, preserving the temperature for 240min and keeping the vacuum degree at 0 Pa; (3) finally, controlling the temperature at 40 ℃ for 120min, preserving the heat for 1200min and keeping the vacuum degree at 0 Pa; the method for detecting the content of the soluble solid in the step (2) comprises the following steps: apple pulp is taken, and soluble solid is detected by an instrument automatic refractometer (Abbemat350) according to a refractometer method for determining the content of the soluble solid of fruits and vegetables NY/T2637-2014.
Preferably, the preparation method further comprises the detection of a standard substance, and the detection method of the standard substance is as follows: taking blank apple pulp, blank apple powder and reference apple pulp to detect the pesticide content; the blank apple pulp and the blank apple powder refer to the apple pulp and the apple powder without pesticide and maltodextrin, silicon dioxide and cellulose powder; the control apple pulp refers to apple pulp with pesticide added, but without maltodextrin, silica and cellulose powder.
In a third aspect, the invention provides the use of an apple powder reference material containing pesticide residues as described above as an apple safety detection capability verification product.
The invention has the advantages that:
1. compared with the prior art, the apple powder of the invention, which is concentrated apple juice and apple jam as reference substances of pesticide residues in apple organisms, has the advantages of easier storage, transportation and taking. In addition, aiming at the problems that the apple contains high sugar content and has low glass transition temperature and the apple powder is easy to agglomerate in the long-term storage process, the agglomeration rate of the finally prepared apple powder is obviously reduced by preferably selecting various raw materials, proportions and experimental parameters thereof, the agglomeration phenomenon can be effectively avoided, and the used additive does not have the adsorption or shielding effect on the pesticide in the apple powder. Experimental results show that the caking rate of the apple powder prepared by the raw materials and the method is as low as 34.79%, and the pesticide content in the apple powder can still keep good stability within 60 days.
2. The preparation method is simple and convenient, the raw materials are wide in source and low in cost, and the prepared product is good in performance. The invention has positive effects on promoting the development of the food matrix reference substance development technology in China and perfecting the food safety monitoring and detecting technology system in China. Meanwhile, the matrix reference substance can be used for organizing and developing capacity verification projects nationwide, can effectively drive and promote the improvement of the technical capacity of food safety monitoring and detecting mechanisms in China, and has good social benefits.
Drawings
FIG. 1 is a technical route for preparing standard substances of an apple matrix.
FIG. 2 shows the preparation process of standard substance of apple matrix.
Fig. 3 is a screen diagram of apple powder to silica and cellulose powder addition ratio of 100:1: 0.5.
Figure 4 is a sieve drawing of apple powder with silica and cellulose powder addition ratio of 100:0.5: 1.
Figure 5 is a screen image of apple powder with a silica and cellulose powder addition ratio of 100:0.5: 0.5.
Detailed Description
The invention will be further illustrated with reference to specific embodiments. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, it should be understood that various changes and modifications can be made by those skilled in the art after reading the disclosure of the present invention, and equivalents fall within the scope of the appended claims.
Example 1
Method and device
1 selection of pesticide addition amount
We determine the adding standard amount of the pesticide in the apple-based standard substance according to the limit standard of the pesticide residue in the apple or the similar fruit specified in GB2763-2019 national standard food for food safety and the response condition of the pesticide on an instrument GC-MS/MS, as shown in Table 1.
TABLE 1 pesticide limits and addition
Adding a scalar quantity: concentration meter in final apple powder
2 optimization of vacuum Freeze drying parameters
We optimized the parameters of vacuum freeze-drying as shown in table 2.
TABLE 2 apple Freeze drying parameters
3 optimization of the preparation Process
We selected a high molecular saccharide additive: maltodextrin, and two anti-caking agents: experiments were conducted with silica and cellulose powders to compare whether the addition of additives improved the caking effect of apple powder. The technical route diagram is shown in fig. 1. Part of the preparation process is shown in FIG. 2.
3.1 apple pretreatment
The apple matrix is selected from organic apples produced in Aksu region of Xinjiang. Removing kernels and stalks, taking pulp, cutting the required sample into small pieces by a knife, and crushing into pulp by a fruit and vegetable crusher.
Leaving about 1kg of apple pulp as blank, taking 500g to directly store at-15 ℃, taking 500g to freeze-dry into powder and storing at-15 ℃. A part of apple pulp is taken to detect the soluble solid content by an automatic refractometer (Abbemat350) of an instrument according to a refractometer method for determining the content of the soluble solid content of NY/T2637-2014 fruits and vegetables, wherein the content is 15.7 percent. And measuring the water content of 82.53% of another part of the apple pulp according to a direct drying method in GB5009.3-2016 national standard for measuring the water content of food safety.
The method for measuring the water content of the apple raw material specifically comprises the following steps of referring to the measurement method of water in food of national standard GB5009.3-2016 of the people's republic of China: baking a flat weighing bottle made of glass in a thermostat at 105 ℃ for about 2 hours, transferring the bottle into a dryer, cooling the bottle to room temperature, weighing the bottle until the weight is accurate to 0.001g, and repeatedly baking, cooling and weighing the bottle until the weight is constant. And scooping about 10g of the crushed and uniformly stirred apple pulp by using a horn spoon, uniformly spreading the apple pulp in a weighing bottle, covering the weighing bottle, and weighing the apple pulp until the weight is accurate to 0.001 g. And obliquely supporting the bottle cap at the bottle edge, and baking for 6 hours in an oven preheated to 105 +/-2 ℃. The mixture was transferred to a desiccator and cooled to room temperature (about 20min) and weighed immediately. Then repeatedly baking, cooling and weighing the mixture to constant weight in a 105 ℃ thermostat. The water content of the apple pulp is measured in 5 portions.
TABLE 3 determination of apple moisture content
3.2 Freeze drying
Weighing 9kg of apple pulp, mixing with 250 μ L of mixed standard solution of four pesticides (deltamethrin, procymidone, quintozene and myclobutanil) dissolved in methanol according to the addition amount in table 1, and uniformly mixing. 500g of the sample was kept as a control and stored at-15 ℃. The remaining 8.5kg of apple pulp was used for the apple base standards preparation of 3.2.1 and 3.2.2.
3.2.1 No addition of maltodextrin
A) 4kg of apple pulp mixture was transferred to a clean freeze-drying tray (charge thickness 6mm) and freeze-dried according to the parameters of Table 2;
B) crushing the dried block sample into powder by a crusher, and sieving the powder by a 35-mesh sieve (500 mu m);
C) uniformly mixing for 24 hours by using a uniformly mixing machine;
D) adding 1% silicon dioxide (1g) by weight into 100g of powder, adding 0.5% cellulose powder (0.5g) and 1% silicon dioxide (1g) into another 100g of powder, and adding no anticaking agent into the rest powder;
E) respectively mixing for 24h by a mixer;
F) and respectively packaging the mixed apple matrix standard substances in 20mL headspace bottles, capping and storing at-15 ℃.
3.2.2 addition of maltodextrin
A) Adding 50% maltodextrin (50% of soluble solid content in apple pulp, namely 4kg × 82.53% × 15.7% × 50%, 259.1g) into 4kg of apple pulp, and mixing;
B) transferring the apple pulp mixture to a clean freeze-drying tray (filling thickness 6mm), and carrying out freeze-drying dehydration according to the parameters of the table 2;
C) crushing the dried block sample into powder by a crusher, and sieving the powder by a 35-mesh sieve (500 mu m);
D) uniformly mixing for 24 hours by using a uniformly mixing machine;
E) adding 1% silicon dioxide (1g) by weight into 100g of powder, adding 0.5% cellulose powder (0.5g) and 1% silicon dioxide (1g) into another 100g of powder, and adding no anticaking agent into the rest powder;
F) respectively mixing for 24h by a mixer;
G) and respectively packaging the mixed apple matrix standard substances in 20mL headspace bottles, capping and storing at-15 ℃.
4 detection of Standard substance
And (3) taking blank apple pulp, blank apple powder, reference apple pulp and 6 kinds of split-packed apple matrix standard substances to detect the pesticide content. After pretreatment with QuEChERS, quantification was performed by GC-MS/MS.
5 detection of anti-caking Properties
The samples and sodium chloride salt without any tea powder or other anti-caking agent (as blank control) were weighed to 7g each, compacted on a tablet press at a pressure of 4Mp and left for 3min, the sample pieces were released, dried in a constant temperature and humidity cabinet for 3h (temperature: 20 ℃, humidity: 80%), dried in an air-drying cabinet at 80 ℃ for 3h after moisture absorption, and then tested for breaking force in a pressure tester, the tests were repeated 3 times, and averaged to obtain an average value, wherein the anti-caking degree is expressed as the caking rate, and the smaller the caking rate (breaking force) is, the better the anti-caking performance is (the caking rate is sample breaking force/kgf + blank salt breaking force/kgf).
6 uniformity measurement
The data obtained were calculated according to the variance method, according to the general principle and statistical principle of standard substance quantitation (JJF 1343-2012).
Average of multiple determinations for one sample:
total average of multiple determinations for all samples:
the sum of the difference between groups:
degree of freedom:
v1＝m-1(n＝3,m＝11)
within-group variance and sum:
degree of freedom:
v2＝m(n-1)(n＝3,m＝11)
variance between groups:
intra-group variance:
as statistic F:
the statistic is a degree of freedom of (v)1，v2) F distribution variable of (2). According to degree of freedom (v)1，v2) And a given significance level α, the critical F α value can be obtained from the F distribution threshold. If the F value calculated according to the formula is F<F alpha, no obvious difference is considered between data groups.
7 stability test
The stability is a measure of the change of the characteristic quantity value of the standard substance with time, and is mainly related to factors such as analyzed physicochemical characteristics, matrix characteristics, storage conditions and the like. When the preparation of the sample is completed and the degradation rate of the compound in the matrix tends to be stable, two bottles of samples frozen at low temperature (-15 ℃) are randomly extracted, the short-term stability (30 days) and the long-term stability (6 months) are monitored according to the principle of first densification and then thinning, and 3 samples to be examined (15 parts in total) are taken each time.
Second, experimental results
1 recovery of pesticide from apple powder
By comparing the pesticide residue content in the standard apple pulp with that in the standard apple powder without the additive (table 4, the recovery rate of pesticide residue in the apple powder is found to be 50.28% -134.32%, wherein the recovery rate of quintozene is the lowest, and the recovery rate of deltamethrin is the highest, the different pesticide recovery rates are probably caused by different extraction efficiencies of QuEChERS on the apple pulp and the apple powder, or pesticide loss in the freeze drying process, and the additive amount is required to be adjusted according to the recovery rate in the preparation process of the apple matrix standard substance at the later stage.
TABLE 4 recovery of pesticide in apple powder
Influence of 2 maltodextrin on water content and pesticide recovery rate in apple powder
The moisture content in the apple powder without maltodextrin was 4.14%, and the moisture content in the apple powder with maltodextrin was 3.05%. It can be seen that the addition of maltodextrin significantly reduced the moisture content of the apple powder. After being placed in an open environment at room temperature, the apple powder without maltodextrin is easier to bond compared with the apple powder with maltodextrin.
Compared with the apple powder without maltodextrin, the recovery rate of the pesticide in the apple powder with maltodextrin is 84-92%, and the maltodextrin does not have the adsorption or shielding effect on the pesticide in the apple powder. Maltodextrin can be added in the preparation process of the apple matrix standard substance at the later stage to reduce the agglomeration phenomenon of apple powder.
3 Effect of anticaking Agents on pesticide recovery
Compared with the apple powder without the anticaking agent, the recovery rate of the apple powder added with the anticaking agent is 87.42-112.90%, and the anticaking agent does not have the adsorption or shielding effect on the pesticide in the apple powder under the adding proportion.
TABLE 5 Effect of anticaking Agents on pesticide recovery
Results of 4 anti-caking Property test
Compared with the apple powder without the anti-caking agent, the apple powder with the anti-caking agent is reduced from 46.21% to 34.78%, so that the caking rate of the apple powder is reduced by 11.42% at the addition ratio, and the anti-caking rate of the apple powder is effectively improved.
TABLE 6 anti-caking Property test results
5 results of uniformity test
This experiment was measured using the method described above. 15 bottles of samples were taken for testing and 3 samples (A, B, C) were taken for each bottle and the results obtained are shown in Table 7 below.
TABLE 7 apple powder pesticide residue uniformity detection data
The uniformity is evaluated by carrying out one-factor variance analysis through SPSS19.0, wherein F is 0.91 calculated from myclobutanil in the apple powder, F is 1.31 calculated from procymidone, F is 0.796 calculated from deltamethrin, F alpha critical values are all 2.04, F is F alpha, and the distribution of myclobutanil, procymidone and deltamethrin in the apple powder is not statistically significantly different, and the capability verification sample is regarded as uniform.
6 results of stability test
6.1 short term stability test
The short term stability of the present study refers to the stability of the standard substance characteristics during transport under the specified transport conditions. According to the general principle and statistical principle of standard substance rating of JJF1343-2012, short-term stability assessment is usually performed under different temperature conditions to examine the influence of temperature on the specific characteristic value of the reference substance.
Since myclobutanil, procymidone and deltamethrin are relatively stable in a low-temperature environment and a cold-chain transportation mode is usually adopted, the work investigates the stability condition of a standard substance under a transportation condition of-15 ℃.3 samples were randomly sampled on 7 th, 14 th and 30 th days from 0 (03/11/2021), and the samples thus sampled were examined.
The results of the experiment are shown in Table 8.
TABLE 8 short term stability test results (mg/kg) of apple powder at-15 deg.C
6.2 statistical analysis of data (straight line fitting method)
Fitting the data in Table 7, wherein x represents time and y represents the characteristic values of the standard substance (the contents of myclobutanil, procymidone and deltamethrin), to a straight line, has a slope of beta1Then, then
According to formula linear intercept
Standard deviation of straight line
Slope uncertainty
Calculating the intercept beta of each content level0Standard deviation s2Slope uncertainty s (β)1) And
the results are shown in Table 9.
TABLE 9 short term stability-statistical parameters of the Linear fitting method
Since the Sig values were all greater than 0.05, the slope was insignificant and no short term instability was observed.
6.3 Long term stability test
The long term stability of the present study refers to the stability of the material properties under specific storage conditions of the reference material.
The results of the experiment are shown in Table 10.
TABLE 10 Long-term stability test results (mg/kg) of apple powder at-15 deg.C
6.4 statistical analysis of data (straight line fitting method)
Statistical analysis was performed according to 6.2 and the results are shown in Table 11.
TABLE 11 Long term stability-statistical parameters of the line fitting method
Since the Sig values were all greater than 0.05, the slope was insignificant and no long-term instability was observed.
The research respectively investigates the short-term stability and the long-term stability of myclobutanil, procymidone and deltamethrin in the apple powder, the test results are respectively analyzed by adopting a linear fitting method, and the statistical result shows that the standard substance has good stability and does not have significant change when being stored for 6 months at the temperature of-15 ℃.
Example 2
The anti-caking effects were compared by adding different proportions of silica and cellulose powder under-15 ℃ storage conditions, and the results are shown in table 12:
TABLE 12 Effect of silica and cellulose powder addition on apple powder agglomeration (-15 ℃ C. storage)
When the apple powder is stored for 6 months and added with different proportions of silicon dioxide and cellulose powder and the mixture is sieved by a CQ-17 sieve (0.408mm, 35 meshes), the results are shown in figures 3-5, wherein figure 3 is a sieving graph when the adding proportion of the apple powder to the silicon dioxide and the cellulose powder is 100:1:0.5, figure 4 is a sieving graph when the adding proportion of the apple powder to the silicon dioxide and the cellulose powder is 100:0.5:1, and figure 5 is a sieving graph when the adding proportion of the apple powder to the silicon dioxide and the cellulose powder is 100:0.5:0.5, and the anti-caking effect is best when the adding proportion of the apple powder to the silicon dioxide and the cellulose powder is 100:1: 0.5.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and additions can be made without departing from the principle of the present invention, and these should also be considered as the protection scope of the present invention.
Claims (10)
1. The apple powder reference substance containing the pesticide residues is characterized by being prepared from the following raw materials: the preparation method of the apple powder reference substance containing pesticide residues comprises the following steps:
(1) pretreatment of apples: removing kernels and stalks of organic apples, taking pulp and crushing into apple pulp;
(2) adding pesticide into apple pulp according to the adding amount, and then adding maltodextrin, wherein the weight adding amount of the maltodextrin is 50% of the soluble solid content in the apple pulp;
(3) pre-freezing, drying and crushing the substance obtained in the step (2) to obtain a powder substance;
(4) adding silicon dioxide and cellulose powder into the powder substance obtained in the step (3), wherein the weight parts of the apple powder, the silicon dioxide and the cellulose powder are as follows: apple powder: silicon dioxide: cellulose powder (100: 1): 0.5;
(5) and (4) putting the substance obtained in the step (4) into a headspace bottle, capping the headspace bottle, and storing the headspace bottle at-15 ℃.
2. The apple powder reference substance with pesticide residues as claimed in claim 1, wherein the pre-freezing conditions in step (2) are: controlling the temperature at minus 40 ℃ for 30min, preserving the heat for 210min and keeping the vacuum degree at 0 Pa; the drying conditions are as follows: (1) firstly, controlling the temperature at minus 5 ℃ for 120min, preserving the heat for 1200min and keeping the vacuum degree at 0 Pa; (2) then controlling the temperature at 5 ℃ for 60min, preserving the temperature for 240min and keeping the vacuum degree at 0 Pa; (3) finally, controlling the temperature at 40 ℃ for 120min, preserving the heat for 1200min and keeping the vacuum degree at 0 Pa.
3. The apple powder reference substance with pesticide residues as claimed in claim 1, wherein the soluble solid content detection method in step (2) is as follows: apple pulp is taken, and soluble solid is detected by an instrument automatic refractometer (Abbemat350) according to a refractometer method for determining the content of the soluble solid of fruits and vegetables NY/T2637-2014.
4. The apple powder reference substance with pesticide residues as claimed in claim 1, wherein the preparation method further comprises the detection of a standard substance by the following method: and (4) taking the blank apple pulp, the blank apple powder and the reference apple pulp to detect the pesticide content.
5. The apple powder reference substance with pesticide residues according to claim 4, wherein the blank apple pulp, blank apple powder refers to apple pulp, apple powder without pesticide and without maltodextrin, silica and cellulose powder; the control apple pulp refers to apple pulp with pesticide added, but without maltodextrin, silica and cellulose powder.
6. The apple powder reference substance with pesticide residues as claimed in claim 1, wherein the preparation method further comprises a performance test experiment on the obtained reference substance, wherein the performance test comprises anti-caking performance test, uniformity test and stability test.
7. A preparation method of an apple powder reference substance containing pesticide residues is characterized by comprising the following steps:
(1) pretreatment of apples: removing kernels and stalks of organic apples, taking pulp and crushing into apple pulp;
(2) adding pesticide into apple pulp according to the adding amount, and then adding maltodextrin, wherein the weight adding amount of the maltodextrin is 50% of the soluble solid content in the apple pulp;
(3) pre-freezing, drying and crushing the substance obtained in the step (2);
(4) adding silicon dioxide and cellulose powder into the powder substance obtained in the step (3), wherein the weight parts of the apple powder, the silicon dioxide and the cellulose powder are as follows: apple powder: silicon dioxide: cellulose powder (100: 1:0.5 parts by weight);
(5) and (4) putting the substance obtained in the step (4) into a headspace bottle, capping the headspace bottle, and storing the headspace bottle at-15 ℃.
8. The method according to claim 7, wherein the prefreezing conditions in step (2) are: controlling the temperature at minus 40 ℃ for 30min, preserving the heat for 210min and keeping the vacuum degree at 0 Pa; the drying conditions are as follows: (1) firstly, controlling the temperature at minus 5 ℃ for 120min, preserving the heat for 1200min and keeping the vacuum degree at 0 Pa; (2) then controlling the temperature at 5 ℃ for 60min, preserving the temperature for 240min and keeping the vacuum degree at 0 Pa; (3) finally, controlling the temperature at 40 ℃ for 120min, preserving the heat for 1200min and keeping the vacuum degree at 0 Pa; the method for detecting the content of the soluble solid in the step (2) comprises the following steps: apple pulp is taken, and soluble solid is detected by an instrument automatic refractometer (Abbemat350) according to a refractometer method for determining the content of the soluble solid of fruits and vegetables NY/T2637-2014.
9. The method according to claim 7, further comprising detecting a standard substance by: taking blank apple pulp, blank apple powder and reference apple pulp to detect the pesticide content; the blank apple pulp and the blank apple powder refer to the apple pulp and the apple powder which are not added with pesticide and are not added with maltodextrin, silicon dioxide and cellulose powder; the control apple pulp refers to apple pulp with pesticide added, but without maltodextrin, silica and cellulose powder.
10. Use of an apple powder reference material containing pesticide residues as claimed in any one of claims 1 to 6 as an apple safety detection capability verification product.
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| CN116671612A (en) * | 2023-06-07 | 2023-09-01 | 华南理工大学 | High-fiber instant full mango powder as well as preparation method and application thereof |
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